What are Hypnic Jerks?

What are Hypnic Jerks?


In the past, you have likely been woken up by the sudden sensation of falling. This is because your body experiences Hypnic jerks. These jerks are also known as sleep starts, and occur before you fall into deep sleep. It is interesting to note how a few scientists view Hypnic jerks from the evolutionary perspective. Taking into consideration that ancestors of humans slept in trees, your body has always been equipped with the fear that you might fall off the tree. Hence, sleep starts are your body’s way to ensure that your muscles aren’t too relaxed and you are still secure.

This article lets you understand what Hypnic jerks really are, making you aware of a common phenomenon that you might be experiencing in your daily lives.

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What is a Hypnic Jerk?

Hypnic jerks can be defined as the involuntary twitch of one or more muscles that occurs as a person falls asleep. As you are woken up by these starts, you might experience increased heart-beat and shallow breaths. The involuntary muscle movement that takes place is known as the myoclonus. You might recognize the occurrence of myoclonus by looking into hiccups, which is caused by the same involuntary movement.

These starts are experienced when a person transitions from a wakeful state to REM (Rapid Eye Movement) sleep. Hypnic jerks are common mainly in the N1, but sometimes also in the N2 stages of sleep (the first two out of four sleep stages). However, they are not experienced every time you go to sleep. Often, the terms Hypnic jerks and Hypnogogic Jerks are confused. However, they are both slightly different.

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Hypnogogic jerks are characterized by muscle twitching that accompanies auditory or visual hallucinations like that of a ghost or an alien. It usually doesn’t startle you to the point where you are woken up from your sleep. Sleep starts are a normal part of the sleep cycle that is experienced by all genders and age groups. However, even though it is common, it isn’t necessary that everyone experiences it. In fact, research has shown that only 60- 70% of people generally experience these jolts. Sometimes, these jolts are weak, and doesn’t wake a person up. People have also described this occurrence as a sensory flash.

Causes of Hypnic Jerks:

While researchers don’t know the exact cause of Hypnic jerks, there are a few speculations related to it. One of them attributes sleep starts to a misfire between nerves present in the reticular brainstem. Another theory is that the brain mistakes the relaxed muscles as a sign of falling and reacts to it by causing this muscle twitch.

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Some factors can increase your likelihood to experience a Hypnic jerk. According to the American Academy of Sleep Medicine, the following are some reasons you experience sleep starts more frequently.

  • Excessive Consumption of Caffeine: Caffeine or other drugs can serve as a stimulant. Since excessive consumption causes trouble in falling asleep, Hypnic jerks are more likely to occur.
  • Deprivation of Sleep: Lack of proper sleep causes extreme tiredness in individuals, poor mood and reduced focus. This increases the chances of experiencing sleep starts.
  • Stress and Anxiety: Stress and anxiety cause an increase in cortisol levels. This doesn’t allow sleep to be restful, contributing to insomnia. Thus, heightened stress and anxiety cause sleep starts.
  • Vigorous Exercise before Sleep: While exercise is good for you, too much of it close to your bedtime causes extreme alertness, making you more vulnerable to Hypnic jerks. In July 2023, a case series was observed to study SSRI-induced Hypnic Jerks. SSRIs (Selective Serotonin Reuptake Inhibitors) are known to cause disturbance in sleep. It also plays a role in causing REM sleep behaviour disorder. The study found a clear association between the use of SSRI medications and causation of Hypnic jerks, and three of the four case reports indicated a probable adverse drug reaction, while the last showed a definite result.

Preventing Hypnic Jerks:

If you are experiencing frequent Hypnic jerks that are causing sleep disturbances, you might be looking for solutions to reduce them. Here are a few ways you can reduce their frequency or intensity.

  • Daily Exercise: A way to stay healthy and relieve stress will help improve your sleep cycle. Remember not to do high-intensity workouts at night.
  • Better Sleep Habits: Set a particular schedule for your sleep as well. Follow the routine and stop using electronics right before bedtime.
  • Minimizing Caffeine Consumption: Keep track of your caffeine intake. It’s okay if you sip on a cup of coffee once in a while, but do not make it an addiction.
  • Reducing Stress: Explore techniques of relaxation that might let you be more calm. If the stress is not manageable, speak to a therapist.

Myths surrounding Hypnic Jerks:

Let’s take a look at some of the misconceptions people hold with regards to Hypnic Jerks and know the facts.

  • It is limited to the feeling of falling: While this feeling is the most common way of experiencing Hypnic jerks, it is not always the case.
  • Everyone experiences sleep starts: Only about 70% of people experience sleep starts.
  • It is a sign of a sleep disorder: While it can be accompanied by a sleep disorder, it is a normal occurring in most cases.
  • It only occurs when you wake up startled: The intensity of Hypnic jerks changes. Sometimes, you don’t wake up when your body experiences sleep starts.
  • Hypnic jerks are near-death experiences: This isn’t true. These jerks are a natural phenomenon that occurs along during the transitional period of wakefulness and REM sleep.

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Are they Dangerous?

Hypnic jerks are a common occurrence, and not at all dangerous. However, it doesn’t mean that you’ll never have to be concerned about it. Although the phenomenon itself is harmless, focus on the effects it has on you. If it is creating a hindrance in proper sleep, it might be a problem. Some people also experience extreme confusion upon waking up startled. Symptoms of bedwetting, tongue biting or physical injury might come forward. If you think that the effects of Hypnic Jerks are affecting you, it might be a good decision to get help. These effects can sometimes be provoked by an underlying sleep disorder. Sometimes, what you think is a Hypnic jerk might be a sleep seizure as well. In these cases, a professional will be best equipped to be your guide.

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